Processes are known, in which a part, for example the commutator of an electric motor, is machined by means of a directional beam of radiation, such as a laser beam. Such a process has been described in German Patent Application 2 733 082.
Such a process presents a considerable drawback in that the radiation impinges on the surface to be machined at a perpendicular angle, this causing it to be reflected by the reflecting faces in a direction parallel to the incident ray. The reflected radiation, conveying energy substantially equal to that used for machining the absorbent faces in turn impinges on the radiation emitting system and destroys it. Furthermore, irregularities on the edge of the surfaces to be machined risk damaging the peripheral masses which are affected by the radiation if it is in a direction perpendicular to the plane of machining. More precisely, for example, machining by radiation normal with respect to the surface of a commutator of an electric motor risks, in the known process, reaching the windings or other sensitive members when the radiation beam extends beyond a part of the surface to be machined due to inevitable, even minute imperfections.
It is an object of the present invention to overcome the above-mentioned drawbacks, i.e. to avoid damage to the system emitting the radiation beam and any damage to the part to be machined. It is a further object to protect the personnel from the reflected radiations, whilst they are still in control on the paths of the reflected radiation. It is another object to propose an installation for carrying out the process which has numerous advantages from the standpoint of safety and a high production rate.